This invention relates to a coated textile fabric for use in an air-holding vehicle occupant restraint system and, more particularly, to a fabric having a plurality of polymeric layers coated thereon for use in such a vehicle occupant restraint system and the method of coating said textile fabric.
The current restraint systems for vehicles include driver side air bags which are housed in the steering wheel in a collapsed, folded condition adapted to be deployed instantaneously in an inflated condition by injection of a gas upon the occurrence of a collision. The advent of such driver-side air bags has resulted in a significant decrease in auto fatalities.
Air bag restraint systems have also been located in the dashboard in order to provide a comparable measure of protection to the passenger seated adjacent the driver.
The automotive industry has recently introduced air bags which are housed in the backs of the front seats or in the rear seats to protect the cabin occupants in the event of a collision occurring on either side of the vehicle.
A still further safety feature which is being marketed for passenger vehicles, especially sport utility vehicles (SUV), are air-holding curtains designed to provide a cushioning effect in the event of roll-over accidents. These curtains are housed in the roof of the vehicle and deploy along the interior sidewalls of the SUV""s cabin in the event of a rollover.
One means of improving the efficacy of air-holding in vehicle restraint systems has addressed the coatings to be applied to the textile substrate to improve air retention.
In the prior art, coated air bags were made by coating a nylon substrate with silicone rubber and chloroprene. They were not, however, susceptible to heat sealing. In order to ameliorate the problems inherent in chloroprene and silicone rubber coatings, it has been disclosed in the art, for example, Menzel et al., U.S. Pat. No. 5,110,666, to coat a woven nylon substrate with polyurethane to provide the desired permeability to better retain the inflation gas.
Despite the advances in air bag coating technology, the problems of controlling air permeability, air pressure, and volume still remain. Another problem resulting in air loss stems from the fact that during the manufacture of the air bags, they are stitched shut by means of sewing. Inherently, each stitch creates a potential leak which adversely affects the integrity and, hence, the air holding capability of the bag, especially when instantaneous deployment of an operative airbag is required.
It has now been found that by applying a plurality of polyurethane coating layers to a knit, woven or non-woven fabric substrate followed by sealing of the layers together by either radio frequency sealing, hot air sealing, or ultrasonic sealing, an air-holding restraint system is obtained which has superior air holding characteristics, viz., permeability, and volume and pressure retention.